I. Field of the Invention
The invention relates generally to a method and related video imaging device coupled to a host computer for communicating video signals to a monitor from a source of video information in response to control data received from the host computer, and specifically to a method and related video imaging device that enables a resultant image on the monitor to be selectively altered with minimal intervention by the host computer.
II. Background Information
In previously known systems, a host computer is coupled by a communication line to a video imaging device. Video information received at the video imaging device from either the host computer or from a local video source is converted at the video imaging device to video signals that are delivered to a monitor for visual display of a corresponding image. In such systems, in order for a user to alter the image displayed on the monitor, the user must initiate events (i.e., push a button, move a pointer) that are received by the video imaging device as user generated event data which is then passed to the host computer over the communication line for subsequent processing. In these cases, instruction data, which is defined as a result achieved from processing the user generated event data by the host computer, is returned to the video imaging device over the communication line. Such video imaging devices alter the resultant display of the image on the monitor in response to the instruction data received from the host computer. The instruction data of such devices is, therefore, entirely defined and controlled by the host computer.
These prior art systems are unacceptable due to the slow speeds of the communication line between the video imaging device and the host computer, thus preventing real-time image alteration in response to the user generated events. For example, if the position of an image on a monitor were to track the movement of a mouse connected to the video imaging device, the instruction data to display the image at the new mouse coordinates will increasingly lag behind the current mouse location as more and more new coordinates are input by the user and sent to the host computer for processing.
In order to avoid the requirement for user generated event data to be communicated between the video imaging device and the host computer, other known systems hardcode desired instruction data into firmware of the video imaging device. Hardcoding the specific instruction data into the firmware of the video imaging device provides the desired response time. Hardcoding is disadvantageous, however, in that it results in the instruction data being totally inflexible. Changing the instruction data requires that firmware memories in the video imaging device storing the instruction data be accessed and physically revised or replaced in order for new instruction data to be executed in response to particular user generated events.